Under the oven broiler, roast the poblano and red bell peppers, turning every 4-5 minutes, until skins are blackened and blistered all over. Move the blackened peppers to a ziploc bag to allow to steam. Once cool enough to handle, remove and discard the skins and seeds. Chop and set aside.
In a medium skillet, melt the butter. Add the mushrooms and cook, tossing regularly, until nicely browned.
In a 13x9 baking dish, toss together the poblano pepper, red bell pepper, mushrooms, croissant pieces, green onion, and parsley. Top with the cheeses.
Combine the eggs, cream, milk, salt, and pepper. Pour over the casserole. Cover with plastic wrap and put in the fridge to set overnight.
Bake casserole at 350°F for 45 minutes or until center is set. Allow to cool 10 minutes before serving. Yields 8 servings.
Calorie count is purely an estimate calculated using an online application to serve as a guide and not to be taken as accurate nutritional information. Percent Daily Values are based on a 2,000 calorie diet.